Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Thorvaldsensvej 57, 1871 Frederiksberg C, Denmark.
Parasit Vectors. 2013 Sep 30;6:286. doi: 10.1186/1756-3305-6-286.
The last decades have seen a considerable increase in urbanization in Sub-Saharan Africa, and it is estimated that over 50% of the population will live in urban areas by 2040. Rapid growth of cities combined with limited economic resources often result in informal settlements and slums with favorable conditions for proliferation of vectors of lymphatic filariasis (LF). In Dar es Salaam, which has grown more than 30 times in population during the past 55 years (4.4 million inhabitants in 2012), previous surveys have indicated high prevalences of LF. This study investigated epidemiological aspects of LF in Dar es Salaam, as a background for planning and implementation of control.
Six sites with varying distance from the city center (3-30 km) and covering different population densities, socioeconomic characteristics, and water, sewerage and sanitary facilities were selected for the study. Pupils from one public primary school at each site were screened for circulating filarial antigen (CFA; marker of adult worm infection) and antibodies to Bm14 (marker of exposure to transmission). Community members were examined for CFA, microfilariae and chronic manifestations. Structured questionnaires were administered to pupils and heads of community households, and vector surveys were carried out in selected households.
The study indicated that a tremendous decrease in the burden of LF infection had occurred, despite haphazard urbanisation. Contributing factors may be urban malaria control targeting Anopheles vectors, short survival time of the numerous Culex quinquefasciatus vectors in the urban environment, widespread use of bed nets and other mosquito proofing measures, and mass drug administration (MDA) in 2006 and 2007. Although the level of ongoing transmission was low, the burden of chronic LF disease was still high.
The development has so far been promising, but continued efforts are necessary to ensure elimination of LF as a public health problem. These will include improving the awareness of people about the role of mosquitoes in transmission of LF, more thorough implementation of environmental sanitation to reduce Cx. quinquefasciatus breeding, continued MDA to high-risk areas, and set-up of programmes for management of chronic LF disease.
过去几十年，撒哈拉以南非洲的城市化进程显著加快，据估计到 2040 年，将有超过 50%的人口居住在城市地区。城市的快速发展与有限的经济资源相结合，往往导致无规划的住区和贫民窟的形成，这为淋巴丝虫病（LF）的传播媒介提供了有利条件。在过去 55 年里，达累斯萨拉姆的人口增长了 30 多倍（2012 年人口为 440 万），此前的调查表明 LF 的患病率很高。本研究调查了达累斯萨拉姆 LF 的流行病学特征，为规划和实施控制提供了背景。
选择了六个离市中心距离不同（3-30 公里）、人口密度、社会经济特征、供水、排水和卫生设施各不相同的地点进行研究。每个地点的一所公立小学的学生接受循环丝状抗原（CFA；成虫感染的标志物）和 Bm14 抗体（传播暴露的标志物）筛查。社区成员接受 CFA、微丝蚴和慢性表现检查。对学生和社区家庭户主进行了结构化问卷调查，并在选定的家庭中进行了病媒调查。
尽管城市化进程混乱，但研究表明 LF 感染负担已大幅下降。可能的促成因素包括针对疟蚊的城市疟疾控制、城市环境中大量库蚊的生存时间短、广泛使用蚊帐和其他防蚊措施，以及 2006 年和 2007 年的大规模药物治疗（MDA）。尽管当前传播水平较低，但慢性 LF 病的负担仍然很高。
迄今为止，进展是有希望的，但仍需继续努力确保 LF 作为一个公共卫生问题得到消除。这将包括提高人们对蚊子在 LF 传播中的作用的认识，更彻底地实施环境卫生措施以减少库蚊的滋生，在高风险地区继续 MDA，并建立慢性 LF 病管理方案。
